Providing references

General Discussion

Advice again please you lovely experienced landlords?
I have some tenants whom I would have loved to have evicted long ago, but have allowed them to stay because (a) they've wanted to and (b) they pay their rent on time every month.
Otherwise these rude people have been a nightmare. Blocking the drains, calling me asking me to collect furniture they have bought because I had a rental van (! which of course I did not do), damaging the property and furniture and they saying the furniture was "s@@t furniture anyway", leaving the property filthy so you could hardly see through the windows, running down the electricity pre-payment meter then calling me saying they had had a power cut!
I am glad that they have just notified me that they are looking for another bigger property but now they are asking for a reference. What do I do? I wouldn't rent to these people (whose 1st language, I have to say, is not English - I have tried to be patient) again on the basis that they have taken up sooo much of my time, have made assumptions, been rude, have caused damage and then not made repairs, and not looked after the property nor the garden.
Can I give a 'factual' reference? Something like saying 'these people have been tenants for X years, and have paid their rent on time'? Just leave it at that?
I don't want any repercussions from saying I wouldn't rent to them again, but that's the reality!
Any advice you can give would be most appreciated.
Thanks.